Grinding wheel



Nov. 3, 1959 E. FUCHS 2,910,810

GRINDING WHEEL Filed April 2, 1958 INVENTOR.

[me/ma Fucw BY @Ww GRTNDENG WHEEL Emanuel Fuchs, Mettmann, Germany, ass? ear to Wagner 8; Englert Gmnhlh, Mettmann lftht hand), Germany, a company of Germany Application April 2, 1958, Serial No. 725,912

4 Claims. (Cl. 51-20-ti) This invention relates to grinding wheels and to processes for the production of grinding wheels of any type of bond, for example ceramic or Bakelite. Known grinding wheels of large diameter can only be effectively worked down to a diameter of a certain smallness on machines employing large diameter wheels. When a grinding wheel has been worn down to such a diameter, it is unsuitable for use as a smaller-dimension whee], both in respect of grain size and of width. For the most part such worn wheels can no longer be used, or are difficult to use. It is known to vary the grain size of grinding wheels in the radial or the axial sense. it is also known to produce grinding wheels whose grain size increases continuously from the centre towards the periphcry of the wheel. Even where the grain size is varied in the radial sense in grinding Wheels of large diameter. the small diameter coarse grain wheel which remains after the outer part of the wheel has been worn down, is too wide, for use in most grinding machines.

According to the present invention there is provided a grinding wheel consisting of an outer annular zone and an inner annular zone, the zones being arranged concentrically about a common bore, wherein the outer said zone extends throughout the whole thickness of the wheel and the inner said zone incorporates at least two juxtaposed portions, a separating layer or separating layers being disposed perpendicularly to the axis of rotation of the wheel and between said juxtaposed portions.

The invention also relates to a process for the production of the grinding wheel according to the invention.

For a better understanding of the present invention and to show how the same may be carried into effect reference will now be made to the accompanying drawing in which,

Figure 1 is a plan view of part of a grinding wheel, and

Figure 2 is a sectional side view of a grinding wheel of the kind shown in Figure 1.

Figure 1 shows, arranged concentrically to one another, a core 4 for the grinding wheel bore 5, an inner filling frame 7, and an outer filling frame 6. A portion of the wheel constituting the outer zone, situated between the two frames 6 and 7, being designated as 3., and the two inner portions (Figure 2) which are situated between the inner frame 7 and the core 4 and are separated by a separating layer 8, are designated 2 and 3.

A method of producing a grinding wheel according to the invention is to place on. a support (not shown) the two frames 6, 7, the heights of which correspond with the thickness of the wheel and the diameter of which corresponds with the diameters of the two grinding wheel zones. the frames being arranged concentrically about a core 4 which defines the wheel bore 5. i The portion 1 of the outer zone is then formed by filling the space between the frames 6 and 7 with a stone mixture suitable for large grinding wheels, up to the full height of the frames. The lower portion 2 of the inner zone is then fQ d. y i g the space between the core 4 and the frame 7 up to a selected height, for example half the height of the frames, with a stone mixture suitable for composing small grinding wheels, 2. separating layer 8 being then applied to the top surface of the portion 2. The portion 3 of the wheel is then formed by introducing on top of separating layer it a stone mixture suitable for composing small wheels, so as to fill with the mixture the remaining space between the core 4 and the frame 7 up to the height of the inner frame, which is removed after the wheel mixture has been fully charged and before pressing.

An advantage of the invention is that when the outer portion 1 of the wheel has been worn by use to such an extent that the diameter of the wheel corresponds to that of the inner frame 7, and traces of the separating layer 8 begin to appear, the two portions 2 and 3 may be separated at the separating layer 8 so that two grinding wheels of the diameter of the inner zone, and having a grain size and wheel width suitable for small grinding wheels. are available for use.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, I declare that what I claim is:

l. A process for the production of a grinding wheel; comprising the steps of arranging two circular filling frames concentrically with respect to each other and about a common core with the height of said frames being at least equal to the thickness of the wheel to be produced, the diameters of said frames corresponding to the diameters of annular Zones to be produced, and then introducing a stone mixture suitable for composing large grinding wheels into the outer space between the outer of said frames and the inner of said frames so as to fill said outer space, then introducing a stone mixture suitable for com posing small grinding wheels into the inner space between the core and the inner of said frames so as to fill said inner space to a predetermined level, then placing a separating layer on the surface of the mixture between the core and the inner frame, further introducing a mixture suitable for composing small grinding wheels into the remaining space between the core and the inner of said frames, then removing said inner of said frames and compacting all of the mixtures under pressure.

2. A grinding wheel comprising an outer annular grinding portion having a predetermined width, a plurality of inner annular grinding portions arranged. completely within said outer annular portion and in side by side relation with respect to each other, said inner annular portions being integrally bonded to said outer annular portion and being coaxial with respect to the latter, and respective separating means intermediate adjacent ones of said inner annular portions and extending perpendicularly with respect to the axis of rotation of said wheel, at least one of said inner annular portions having a width substantially smaller than said predetermined width of said outer annular portion.

3. A wheel as claimed in claim 2, wherein the inner annular grinding portions are of a different grain size and are of a different hardness from said outer annular grinding portion.

4. A wheel as claimed in claim 2, wherein there are two equal inner annular portions, each portion being half the thickness of the wheel.

References Cited in the file of this patent UNITED STATES PATENTS 687,962 Hyde Dec. 3, 1901 2,004,630 Krug June 11, 1935 2,069,116 Sanford Jan. 26, 1937 2,479,079 ,Reid Aug. 16, 1949 

